  #include "web_log.h"
  #define MAX_CALLBACKS 32

  typedef struct {
      log_LogFn fn;
      void *udata;
      int level;
  } Callback;

  static struct {
      void *udata;
      log_LockFn lock;
      int level;
      bool quiet;
      Callback callbacks[MAX_CALLBACKS];
  } L;


  static const char *level_strings[] = {"TRACE", "DEBUG", "INFO", "WARN", "ERROR", "FATAL"};

  #ifdef LOG_USE_COLOR
  static const char *level_colors[] = {"\x1b[94m", "\x1b[36m", "\x1b[32m", "\x1b[33m", "\x1b[31m", "\x1b[35m"};
  #endif


  static void stdout_callback(log_Event *ev) {
      char buf[16];
      buf[strftime(buf, sizeof(buf), "%H:%M:%S", ev->time)] = '\0';
      #ifdef LOG_USE_COLOR
          fprintf(ev->udata, "%s %s%-5s\x1b[0m \x1b[90m%s:%d:\x1b[0m ", buf, level_colors[ev->level], level_strings[ev->level], ev->file, ev->line);
      #else
          fprintf(ev->udata, "%s %-5s %s:%d: ", buf, level_strings[ev->level], ev->file, ev->line);
      #endif
      vfprintf(ev->udata, ev->fmt, ev->ap);
      fprintf(ev->udata, "\n");
      fflush(ev->udata);
  }

  static void file_callback(log_Event *ev) {
      char buf[64];
      buf[strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", ev->time)] = '\0';
      fprintf(ev->udata, "%s %-5s %s:%d: ", buf, level_strings[ev->level], ev->file, ev->line);
      vfprintf(ev->udata, ev->fmt, ev->ap);
      fprintf(ev->udata, "\n");
      fflush(ev->udata);
  }

  static void lock(void)   { 
      if (L.lock) { 
          L.lock(true, L.udata); 
      }
  }

  static void unlock(void) {
      if (L.lock) { 
          L.lock(false, L.udata); 
      }
  }

  const char* log_level_string(int level) { 
      return level_strings[level];
  }

  void log_set_lock(log_LockFn fn, void *udata) {
      L.lock = fn;
      L.udata = udata;
  }

  void log_set_level(int level) {
      L.level = level;
  }


  void log_set_quiet(bool enable) {
      L.quiet = enable;
  }


  int log_add_callback(log_LogFn fn, void *udata, int level) {
      for (int i = 0; i < MAX_CALLBACKS; i++) {
          if (!L.callbacks[i].fn) {
              L.callbacks[i] = (Callback) { fn, udata, level };
              return 0;
          }
      }
      return -1;
  }


  int log_add_fp(FILE *fp, int level) {
      return log_add_callback(file_callback, fp, level);
  }


  static void init_event(log_Event *ev, void *udata) {
      if (!ev->time) {
          time_t t = time(NULL);
          ev->time = localtime(&t);
      }
      ev->udata = udata;
  }

int log_init(const char *filename) {
    FILE *fp = fopen(filename, "a+");
    if(fp == NULL){
            printf("create log file failed.\n");
            return -1;
    }

    //设置日志级别(在终端打印)
    log_set_level(LOG_TRACE);

    //设置日志级别(在文件中打印)
    log_add_fp(fp, LOG_INFO);

    return 0;
  }


  void log_log(int level, const char *file, int line, const char *fmt, ...) {
      log_Event ev = {
          .fmt   = fmt,
          .file  = file,
          .line  = line,
          .level = level,
      };

      lock();

      if (!L.quiet && level >= L.level) {
          init_event(&ev, stderr);
          va_start(ev.ap, fmt);
          stdout_callback(&ev);
          va_end(ev.ap);
      }

      for (int i = 0; i < MAX_CALLBACKS && L.callbacks[i].fn; i++) {
          Callback *cb = &L.callbacks[i];
          if (level >= cb->level) {
              init_event(&ev, cb->udata);
              va_start(ev.ap, fmt);
              cb->fn(&ev);
              va_end(ev.ap);
          }
      }

      unlock();
  }
